Kotoshogiku celebrates with his supporters after winning the Emperor’s Cup.
Photograph: Kyodo/Reuters

Japan’s agonising wait for a homegrown sumo champion has ended after Kotoshogiku on Sunday became the first Japan-born wrestler in a decade to win a tournament.

The 31-year-old claimed the Emperor’s Cup and sparked wild celebrations inside the arena after throwing his opponent, Goeido, to the ground to end the new year tournament in Tokyo with an unassailable 14 wins and one loss.

Kotoshogiku throws Goeido down in the ring to win the championship. Photograph: Yoshinobu Shimizu/AP

His victory could mark the beginning of a challenge to years of domination by Mongolian wrestlers, and reignite interest in the ancient sport among younger Japanese people.

The overseas sumo onslaught began with Konishiki and other Hawaiian wrestlers in the 1990s, and continued into the next decade with the arrival of the Mongolian wrestler Asashoryu, whose brilliance in the ring was sometimes tarnished by bad behaviour off it.

Until Sunday, no Japan-born wrestler had won a tournament since Tochiazuma exactly a decade ago, and the sport has not had a Japanese grand champion, or yokozuna, since Takanohana retired in 2003.

Kotoshogiku broke into a beaming smile as the scale of his accomplishment sank in. His parents, who were in the crowd, burst into tears, and relatives and friends watching on a big screen in his hometown of Yanagawa, in south-western Japan, erupted in celebration.

“It’s hard to find the words to describe how I feel,” said Kotoshogiku, who stands 5 feet 10 inches tall and weighs 180 kilos (28st 4oz).

“I am so delighted … I thought about the tough times when I struggled [with injury] and my record was poor, but I have come this far with the support of so many people and the guidance of my stable master.”

Traditionalists will hope that Kotoshogiku’s victory marks the beginning of a new era for sumo, whose reputation has been hit in recent years by a series of scandals, including allegations of bout fixing, gambling and drug taking.

Perhaps the most damaging incident occurred in 2007, when a 17-year-old recruit died following an assault by three senior wrestlers on the orders of their stable master.

It remains to be seen whether Kotoshogiku, who holds the rank of champion or ozeki, can end the domination of the three reigning grand champions, all of whom are Mongolian.

Hakuho, considered by many to be the greatest sumo wrestler of all time, has notched up a record 35 tournament victories since May 2006, while his fellow Mongolian, Harumafuji, has seven tournament wins.

Kotoshogiku, who performs a crowd-pleasing backward stretch before each bout, beat all three yokozuna in Tokyo, losing just once to his childhood friend Toyonoshima.

Toyonoshima, who at one point was a contender for the title, embraced his rival after his victory. “His win meant this was both the saddest and happiest day for me,” he said. “I’m just looking forward to the next time we are both in contention.”

Three professional tournaments are held in Tokyo during the year, while Osaka, Nagoya and Fukuoka host one each.